Apparatus for changing speed and direction of rotation by reversing a constant speed motor



Feb. 19, 1935. B, z c 1,991,756

. APPARATUS FOR CHANGING SPEED AND DIRECTION OF ROTATION BY REVERSING ACONSTANT SPEED MOTOR Filed March'SO, 1933 ToLoadfl DS L5 *I 615 6/ 4 18C [1116, 14/ J {129 @1150 12 3; R1 U 11 mg 11 '55s 40 4, 56 M 7 M@ W 466 INVENTOR y Bpazzko Laz'zfc'lz A TTORNE Y operation of a mechanism witha change in the the apparatus embodying my invention may. be 5 PatentedFeh. 19, 1935 entree stares APPARATUS FOR CHANGING SPEED AND DIRECTIONOF ROTATION BY BEVERSING MOTOR Branko Lazich, Edgewood, Pa., assignor toThe Union Switch & Signal Company, Swlssvale, I'm, a corporation ofPennsylvania Application March 30, 1933, Serial No. 663,440

4 Claims.

My invention relates to apparatus for changing the speed and directionof rotation of a mechanism, and has for an object novel and improvedmeans to obtain a change in the speed of direction of rotation byreversibly operating a constant speed motor.

-I will describe three forms of apparatus embodying my invention, andwill then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a view partly diagrammatic andpartly in section of one form of apparatus embodying my invention. Fig.2 is a sectional view at the line 11-11 of Fig. 1. Fig. 3 is a sectionalview of a second form of apparatus embodying my invention, and Fig. 4 isa sectional view along the line 1V---IV of Fig. 3. Fig. 5 is a plan viewof a third form of appara-- tus embodying my invention, and Fig. 6 is asec tional view at the line VI-VI of Fig. 5.

In each of the several views like reference charf acters designatesimilar parts.

It has been proposed to control a highway crossing signal located at theintersection of a highway and a railway at grade in such a manner thatthe signal is operated a constant time interval before a train reachesthe intersection regardlessgof the speed of the train. Such controlinvolves a mechanism for determining the speed of the train as itapproaches the intersection and for subsequently starting theoperationof the signal in accordance with the measured speed. It isdesirable to determine the speed of a train while the train istraversing a-relatively short track jsect-ion, much shorter than therequired operat-' ing section; and furthermore, it is desirable tooperate the mechanism while determining the speed of the train and whiledetermining the time for starting the operation of the signal by asingle motor, the motor operating at a constant speed throughout theentire period. Such requirements necessitate not only achange in thedirection of operation of the mechanism when a train reaches a fixedpoint; but also a change inthe speed of operating the mechanism, aconstant speed reversible electric motor being a reliable and efficientdriving unit. A feature of my invention is the provision of novel andreliable means for selecting the speed and direction of rotation of anoperating shaft by selecting the direction of operation of a constantspeed motor. Other features of my invention will appear as thespecification progresses. v

Many different applications for the apparatus of my invention willnaturally suggest themselves With relay 4 deenergized and relay 3energized cuit extending from one terminal of battery 2 tothose skilledin the art, and it will be understood that I do not wish to limit myselfto the specificcase cited above; this one case will serve, however, toillustrate the many different places employed- Y Referring to Fig. 1, Mdesignates a constant speed motor of any of the many well known-types,and in this'instance is shown as a direct current motor .ireversiblysupplied with current from a battery \through the medium of twocontrolling relays 3 and'4. Relays 3 and 4 may be controlled in anyconvenient manner, such for example, as by standard railway trackcircuits not shown. When both relays 3 and 4.- are energized asillustrated in the drawing, current is supplied to neither the fieldwinding 5 nor to the armature 6 of the motor M and the motor isinactive.

the field winding 5 of motor M is excited by current from the battery 2over a circuit easily traced and which includes the two back contacts 30and 31of relay 4. The armature 6 of motor M receives current-from thebattery 2 by a cir- 25 over back contact 30 of relay 4, front contact 10of relay 3, armature 6, front contact 9 and back contact 31 to theopposite terminal-of the battery 2. Under this condition the directionof the flow of current in the armature 6 is such as to cause the motor Mto rotate, say, in a clockwise direction at its given constant speed.Deenergizing both relays 3 and 4 causes the field winding 5 to beexcited the same as before, but the circuit for the armature 6 is nowfrom the top terminal of battery 2 over had; contact 30, back contact 7of relay 3, armature 6, and back contacts 8 and 31 to the oppositeterminal of battery 2. The direction of the current flow in the armature6, is reverse to that of the former case and the motor M is operated ina counter-clockwise direction at its given constant speed. It followsthat when both relays 3 and 4 are energized, the motor M is'inactive;when relay 4 is deenergized and relay 3 is energized, the motor M' isrotated 45 clockwise at its given constant speed; and with both relays 3and '4 deenergized, the motor M is rotated counter-clockwise atits-given constant speed. It will be understood, of course, that manyother ways may be readily employed to reversibly 50 supply current tothe motor M to cause it to rotate clockwise at one time "and to rotatecounter-clockwise at another time.

As shown schematically in Fig. 1, the motor M is operatively connectedwith a shaft 11, and

.- ll'likewise rotates clockwise at a given constant speed; and when themotor is rotated counterclockwise at its given constant speed, the'shaft11 likewise rotates counter-clockwise at its given constant speed.

Loosely mounted on the motor shaft 11 is a gear G1, on the'arbor 12 ofwhich is keyed a ratchet R1. mounted a second gear G2 on the arbor 13 ofwhich is keyed a second ratchet R2. The physical arrangement of theseparts will be readily understood by an inspection of Fig. 1, theratchets R1 and R2 being arranged for opposite operation as shown inFig. 2. An arm 14 is rigidly fastened to the motor shaft 11 by a pin 52,and arm 14 carries a pin 15 which fits into a yoke 16 of a ratchet pawl17 as is best shown in Fig. 2. The pawl 17 is supported by a pin 18attached to a collar 19 which fits on the arbor 13 of gear G2 with aslight amount of friction between collar 19 and the arbor 13 so thatwhen the direction of rotation is reversed as will be shortly pointedout, the pawl 17 is. driven positively into engagement with the properratchet R1 or R2. Gear G1 meshes with a gear G3 pinned to an operatingshaft DS by a pin 53, the gear ratio between gears G1 and G3 beingarranged as desired. Gear G2 meshes with a gear G4 which is likewisepinned to the operating shaft DS by a pin 54, the gear ratio betweengears G2 and G4 being arranged as desired. In Fig. 1 the gears G1 and G3are selected to produce a reduction in the speed of rotation so that theoperating shaft DS is driven at a speed of rotation less than thedriving gear G1 when that gear is active. Gears G2 and G4 are selectedto produce an increase in the speed of rotation so that the operatingshaft DS is driven at a speed of rotation greater than that of thedriving gear G2 when that gear is active. The operating shaft DS maybeconnected to any desired load,

such for example, as the constant time warning mechanism for a highwaycrossing signal referred to hereinbefore.

When the motor M and the shaft 11 are rotated in a clockwise directionas viewed in Fig. 1

(counter-clockwise when viewed in Fig. 2) the viewed in Fig. 2) the pin15 causes the pawl 1'!- to tilt to the left (right in Fig. 2) andengage. the ratchet R1, ratchet R1 being arranged reverse to ratchet R2-as pointed out above. Ratchet R1 in turn drives the gear G1 and theoperating shaft DS is rotated clockwise at a speed of rotationdependingupon the ratio be.- tween gears G1 and G3. Under this condition theratchet R2 and gear G2 are free-to turn so that when they are driventhrough the gear G4,

they offer no ap reciable load .to the motor M. It is clear from theforegoing description that the direction of rotation of the motor Mselects the ratchet and gear train by which the operating shaft DS is tobe operated. The different 1,991,756 thus it follows that when themotorM is rotated On'the arbor 12 of gear-G1 is loosely gear ratios forthe two different gear trains cause the shaftDS to be drivencounter-clockwise at one speed when the motor M is operated clockwise atits constant speed, and to be driven clockwise at a different speed whenthe motor M is reversed and operated counter-clockwise at its constantspeed.

Referring to Figs. 3 and 4, a friction clutch arrangement for selectingthe direction of rotation and for selecting the gear train by which theoperating shaft is to be driven is disclosed. This clutch arrangementcomprises a clutch case CC, a drive drum DD, clutch segments CS, and aclutch drive plate CDP, all mounted upon the operating shaft DS. Thedrive drum. DD is keyed to the shaft DS by a key 50, but the drive plateGDP and the clutch case CC are both free to rotate on the shaft DS. Theclutch segments CS are made to fit loosely between the outer face ofthedrum DD and the inner face of the case CC. 20

Each segment CS is provided with a slot 55 the two extreme ends of whichare of unequal radii with respect to the cc iter of the shaft DS, aswill be readily understood by an inspection of Fig. 4.

The clutch drive plate GDP is provided with three motor shaft 11. Theclutch case CC is equipped with a gear 22 which engages a gear 23adapted to freely rotate on an idle shaft 24. A gear 25 on thehub ofgear 23 engages the gear RG which as stated above is keyed to theoperating shaft DS.

The operation of this clutch arrangement is such that when theclutchplate GDP is driven in a counter-clockwise direction, the pins Pmove 40 along the slots 55 to force the clutch segments CS toward thecenter and these segments are .made to clutch the outer face of thedrive drum DD with the result that the operating'shaft 'DS is driven ina counter-clockwise direction. When 4 the clutch plate GDP is driven inthe clockwise direction, the pins P move along the slots 55 to force theclutch segments CS outward, and the segments CS are made to clutch theinner face of the clutch case CC with the result that the clutch case isrotated a clockwise direction. Under this latter condition, the gear 22drives the gear 23, and gear 25 on the hub of gear 23, in turn drivesthe gear RG, with the result that clockwise rotation of the clutch caseCC causes a clockwise rotation of the operating shaft DS. Hence,operating the motor M in a direction to rotate the plate GDP in acounter-clockwise direction causes the drum DD and the operating shaftDS to be rotated in a counter-clockwise direction, the speed of rotationof shaft DS being in accordance with the gear ratio between the gear 20and the pinion 21. Under this condition of operation the clutch segmentsCS are drawn away from the clutch case CC and it is free to 05 be drivenby the shaft DS through the gear train comprising gears RG, 25, 23 and22 without appreciable load to the motor M. Reversing motor M and thusrotating the plate GDP in a clockwise The clutch plate GDP is equipped3o with a gear 20 which engages a pinion 21 on the direction, the clutchcase CC is engaged by the segments CS and the shaft DS is rotated in aclockwise direction at a speed of rotation depending upon the gear ratioof the gear train comprising the gears 21, 20, 22, 23, 25 and RG.

Under this condition of operation the clutch se'g- 76 ea p 1,901,750

; appreciable load to the motor M.

Referring to Figs. 5 and 6, another clutch and gear train mechanismfor-driving an operating shaft in opposite directions at differentspeeds by reversing a constant speed motor is disclosed. The motor shaft11 is coupled with the motor M by any suitable means the same as 'inFig. 1, androtates at a constant speed clockwise or counterclockwise inaccordance with the direction oi!v operation of the motor M. A ratchet33 fits loosely on shaft 11.and has rigidly fastened to its hub 34 agear 35. -A second ratchet 36 fits loosely on shaft 11 and has rigidlyfastened to its hub'37 a gear 38. A screw thread 32 is cut on theshaft11 and engages a ratchet nut RN causing it to move along the axis of theshaft 11 thereby engaging either the ratchet 33 or the ratchet 36 todrive either the gear or the gear 38. The gears 35 and 38 engage gears39 and 40, respectively, which are fastened to the operating shaft DS bypins fl'and 42, respectively. A compression spring 43 is provided inback of gear 35 and is held in place by a cup 44 pinned to the shaft 11by a pin 45. In like manner a compression spring 46 is provided in backof gear 38 and is held in place by a cup 4'1 pinned at 48 to the shaft11.

Operating the motor M of Fig. 6 in one direc tion causes the shaft 11 torotate in a corresponding direction and the ratchet nut RN is driven,say, to the right to engage the ratchet 36, and hence drive theoperating shaft DS in a. clockwise direction through the-train of gearscomprising gears 38 and 40. The speed of rotation of shaft DS is, inthis instance, increased in proportion to the ratio of gears 33 and 40.Under this condition of operation the gear 35 and its'associated atchet33 are free to rotate when driven by the shaft DS through gear 39. Re--versing the motor M to drive shaft 11 in the reverse direction moves theratchet nut RN to the left out of engagement with the ratchet 36 andinto engagement with the ratchet 33. The shaftDS is now rotated in acounter-clockwise direction through the train of gears comprising gears35 and 39, the speed of rotation of shaft DS being reduced in proportionto the ratio of gears 35 and 39. This time the ratchet 36 and the gear38 are free to rotate when driven by shaft DS through the medium of thegear 40.

The compression springs 43 and 46 provide a .certain amount of give incase the tops of the ratchet teeth of the ratchet nut RN engage with thetops of the teeth of ratchet 33 or 36 asthe case may be, the slightmotion permitted by these compression springs being sufficient to permitthe .two sets of ratchet teeth to slip sufficiently to engage with eachother.

It is clear from the foregoing descriptions of Figs. 5 and 6 that. twodifferent speeds'of rota- .tion of shaft DS are obtained by reversingthe constant speed motor M. It is to be noted that with the ratchets 33and 36, and the ratchet nut RN all mounted directly on the motor shaft11, a reversal in the direction of rotation of the operating shaft DSimmediately follows a reversal in the direction of operation of themotor M.

Mechanisms such as here disclosed provide a simple and reliable meansfor changing the speed of rotation with a reversal in the direction ofrotation by reversing a constant speed motor.

Although I have herein shown'and described only three formsof apparatusembodying my insecond ratchet mounted loosely on the motor shaft andhaving rigidly mounted on its hub a. gear in mesh with said second gear,said ratchets spaced apart and facing each other, a screw 15 threadformed on the motor shaft between said ratchets, a nut engaging thescrew thread and having ratchet teeth formed on its opposite endsadapted to engage with the teeth of said first and second ratchetsrespectively, a motor operatively 20 connected with the motor shaft,control means for reversibly-operating the motor to move said nut intoengagement with one or the other ratchetsfor driving the operating shaftthrough either I said first or second gears, a first cup pinned to 25the motor shaft-, adjacent the face of the gear mounted on said firstratchet remote from the ratchet, a second cup pinned to the motor shaftadjacent the face of the gear mounted on the second ratchet remote fromthe ratchet, and a' 30 spring fitted in each of said cups to exert aforce on the associated gear whereby full engagement between the teethof the nut and the teeth of the particular ratchet when the nut isdriven toward that ratchet is assured.

2. In combination, an operating shaft, a first and a second gearrigidly-mounted onsaid shaft, a motor shaft, a first ratchet mountedloosely on the motor shaft and having rigidly mounted on its hub a gearin mesh with said first gear, a 40 second ratchet mounted loosely onthemotor shaft and having rigidly mounted on its hub a gear in mesh withsaid second gear, said ratchets spaced apart and facing each other, ascrew thread formed on the motor shaft between said 45 ratchets, a nutengaging the screw thread and having ratchet teeth formed on itsopposite ends adapted to engage with the teeth of said first and secondratchets respectively, a motor operatively connected with the motorshaft, control 50 means for reversibly operating the motor to move saidnut into engagement with one or the other ratchets for driving theoperating shaft through either said first or second gears, a first meanspinned to the motor shaft. adjacent the face of 55 the gear mounted onsaid first ratchet remote from the ratchet and including a compressionspring for providing a give in case the tops of the teeth of the nutengage the tops of the teeth of the ratchet as the nut is driven towardthat 6 ratchet, and a second means pinned to the motor shaft'adiacentthe face of the gear mounted on said second ratchet remote from theratchet and including a compression spring for providing a give in casethe tops of the teeth of the nut en- 65 gage the tops of the teeth ofthe ratchet as the nut is driven toward that ratchet.

3. In combination, an operating shaft, 9. motor; a motor shaftoperatively connected with said motor, control means for reversiblyoperat- 70 ing the motor, a first gear train including a gear rigidlymounted onthe operating shaft and another gearlooselymounted on themotor shaft, a second gear train including a gear rigidly mounted on theoperating shaft and another gear 75 loosely mounted on the motor shaft,said gear trains being spaced apart on the shafts, a first ratchetfastened to said other gear of the first gear train, a second ratchetfastened to said other gear of the second gear train, said ratchetsbeing mounted on the respective gears to face each other, a screw threadformed on the motor shaft between the gear trains, a nut engaging thescrew thread foroperation along the motor shaft in accordance with thedirection of rotation of said shaft, ratchet teeth formed on each end ofthe nut for engaging with the teeth of said first and secondratchetsrespectively for driving the operating shaft through the firstor the second gear train according to the direction of operation of themotor, a first means rigidly mounted on the motor shaft adjacent saidother gear of the first gear train remote from the associated ratchetand including a yielding member engaging the gear, and a second meansrigidly mounted on the motor shaft adjacent said other gear of thesecond gear train remote from the associated ratchet and including ayielding member engaging the gear.

4. In combination, an operating shaft, a motor, a motor shaftoperatively connected with said motor, control means for reversiblyoperating the motor, a first gear train including a gear rigidly mountedon the operating shaft and another gear loosely mounted on the motorshaft, a second gear train including a gear rigidly'mounted on theoperating shaft and another gear loosely mounted on the motor shaft,said gear tr'ains being spaced apart on the shafts, a first ratchetfastened to said other gear of the first. gear train, a second ratchetfastened to said other gear of the second gear train, said ratchetsbeing mounted on the respective gears to face each other, a screw threadformed on the motor shaft between the gear trains, a nut engaging thescrew thread for operation along the motor shaft in accordance with thedirection of rotation of said shaft, ratchet teeth formed on each end ofthe nut for engaging with the teeth of said first and second ratchetsrespectively for driving the operating shaft through the first or thesecond gear train according to the direction of operation of the motor,a first collar rigidly mount-. ed on the motor shaft outside said othergear of the first gear train and having a recess in its face adjacentthe gear, a second collar rigidly mounted on the motor shaft outsidesaid other gear of the second gear train and having a recess in its faceadjacent the gear, and a compression spring fitted into each of saidrecesses to engage. the associated gear for providing a yielding in casethe tops of the teeth of the nut engage the tops of the teeth of theratchet mounted on the associated gear as the nut is driven toward thatratchet.

- BRAIYKO LAZICH.

